Mitochondrial fission

In healthy cells, mitochondrial fission and fusion are balanced, and disruptions to these processes are linked to various diseases.

[3] Mitochondrial fission plays a role in the cellular stress response and in apoptosis (programmed cell death).

The head region is the GTPase (G) domain, while the neck is composed of three bundle signaling elements (BSEs).

In yeast cells (a common model for studying mitochondrial fission), the outer membrane protein Fis1 associates with Mdv1 and Caf4, which in turn recruit Drp1.

Calcineurin, activated by increased calcium ion levels, can dephosphorylate the Ser637 site, thus promoting fission.

Bundles of actin cross diagonally at these sites, recruiting myosin II, which assists in localizing Drp1 to the mitochondria.

[11] Actin bundles serve as reservoirs of Drp1 proteins, providing a pool for assembly onto the mitochondrial surface.

Actin polymerization also triggers calcium ion influx from the ER into the mitochondria, resulting in the dephosphorylation of Ser637 on Drp1, leading to mitochondrial fission.

Midzone division is linked to mitochondrial biogenesis, which occurs when the cell is proliferating and requires an increased number of mitochondria.

In contrast, peripheral division is associated with the removal of damaged mitochondrial units from the network, with these mitochondria being targeted for autophagy or mitophagy, leading to their degradation.

Peripheral division is often preceded by elevated concentrations of reactive oxygen species (ROS), as well as reduced membrane potential and pH.